THE GEOLOGY OF THE MALAY PENINSULA. 243 
stone of Yunnan, Indo China, and China resembles the limestone 
of the Shan Spates suggests that, with the close of the Devonian 
period, the submergence advanced northwards. 
Carboniferous and Permian. 
In Indo-China and Cochin-China there was an unconformity 
between the shallow-water Devonian rocks and the succeeding Car- 
boniferous limestones. The lower horizons of themiddle Carbonifer- 
ous limestones of Eastern Yunnan are sandy, and of a shallow- 
water type, which passes upwards into a sandy coal-bearing series 
with subordinate limestones, and then, in the western part of East 
Yunnan, into deep-water limestones. In the eastern area earth- 
movements took place, resulting in folds running in a northeast- 
southwest direction, and the denudation of these folds resulted in 
sandy sediments dha ne the middle Carboniferous period, while the 
limestones imterbedded with basic lavas were laid down during 
local periods of stability. 
Then slow submergence took place, and enormous thicknesses 
(about 5000 ft.) of massive limestones now cover the area. In the 
eastern area there is a distinct break in the stratigraphical sequence, 
‘between the lower part of the middle Carboniferous and the upper 
Carboniferous limestones, owing to the folding movements just 
described, but the conditions during the greater part of the upper 
Carboniferous period were uniform deep water, resulting in an 
uninterrupted serves of limestones, which are responsible for the 
unusual scenery of Eastern Yunnan at the present day. In the 
ease of the folded series of middle Carboniferous sands and inter- 
bedded limestones the sandy beds have been denuded away easily, 
leaving the limestone standine out as prominent scarps, but the 
upper Carboniferous series of limestones, without sandy bands, 
has given rise to the Karst type of scenery, so called from the Karst 
district in Austria, dry, and almost waterless, with pot-holes and 
underground streams. 
These Carboniferous limestones are of a very widespread nature, 
occuring in practically the whole of Indo-China, the Malay Penin- 
sula, Sumatra, and in the islands of Rotti and Timor in the Archi- 
pelago, where they pass conformably up into the Permian. Permo- 
Carboniferous limestones are not very strongly developed in the 
Northern Shan States, for they have been greatly denuded there, 
and merely form a band lying on the Plateau Limestone. They differ 
from, the latter in not being so intensely crushed. 
In the Malay Peninsula they form very prominent groups of 
hills, with vertical cliffs up to 2000 ft., separated by intervening 
expanses of flat land with an irrezular surface of pinnacles and 
solution-hollows, covered and smoothed over with alluvium. The 
type of scenery here displayed is quite different from the karstic 
type of Yunnan and the Shan States, although the limestone in the 
Peninsula too is very uniformly free from sandy bands. The 
difference is due to the fact that, in the Peninsula, the limestone 
R. A. Soc., No. 86 1922 
